THE PHILADELPHIA LIBRARY NEW HAVEN, COMd. MEDICAL AND PHYSICAL JOURNAL. I. Observations and Experiments on the extraordinary degree of Cold, at Northampton (a midland county in England), during the Intense Frost of 1776-7. With Remarks on the Climate of London, Philadel phia, &c. In a letter to a friend. By A. FOTHERGILL, M. D., F. R. S., &c., and by him communicated to the EDITOR. "Vides ut alta stet nive candidum Soracte; nec jam sustineant onus Flumina constiterint acuto !" HORACE. IN compliance with your request, my dear friend, I shall now lay before you some account of my observations and experiments, made during the uncommonly severe frost of 1776-7. As some of the phenomena appeared to me not a little surprizing, I minuted them down at the time they occurred. The cold season commenced towards the close of December, 1776; and on January 27th, 1777, the immense quantity of snow which had fallen, within the last three weeks, had now rendered many of the roads impassable, and, in a great measure, cut off all intercourse between the metropolis and the northern parts of the kingdom; the snow, in consequence of a high wind, being drifted, in many places, to the height of more than twelve feet, presenting a prospect awfully sublime and picturesque, and exhibiting win<ter arrayed in all its horrors. This morning the frost became suddenly more severe, the wind full east, accompanied with incessant snow. The barometer stood at 293; Fahrenheit's thermometer, which hung in my parlour, where there was a good fire, stood at 33°, barely one degree above the freezing point. On being removed into the open air, it presently sunk to 20°. At five o'clock, the same evening, it fell to 16°. At this time, eggs, exposed in the market, were found completely frozen, assuming the consistence of wax. Experiment 1. This evening was placed on my garden wall, facing the north-east, an ounce of lemonjuice, of vinegar, and of red port-wine, in three china saucers. January 28th. This morning, at eight o'clock, the barometer at 30°, the thermometer at 12°, wind northeast, the three liquors were each of them reduced to a solid cake of ice. Experiment 2. This night, about eleven, were placed on the same wall the following liquors, viz. : spirit of mindererus (which has since been termed acetated ammonia), volatile spirits of sal ammoniac (both kinds, mild and caustic), dulcified spirit of nitre, red wine, and French brandy. January 29th. Barometer 29°, thermometer 9°, the north-east wind excessively keen and piercing; the roads, which, by dint of great labour and expence, had just been cut through, to enable carriages to pass, were again completely drifted up. The several liquors above-mentioned, to my great surprise, now showed evident marks of freezing. Experiment 3. They were suffered to remain all night, and two more cups were placed near them, with highly rectified spirit of wine (alcohol), and rectified vitriolic æther. January 30th. The morning clear, but intensely cold; wind north-east; barometer 30%; thermometer sunk to 3°, viz. 29 degrees below the freezing point! a degree of cold which, I apprehend, has been but rarely experienced in this climate, being considerably below that of the remarkable frost of the year 1739-40*. And yet the above was not the greatest degree of cold; for (having no opportunity to examine the * The greatest degree of cold observed, during that uncommonly severe winter, was only 13, as appears from a record in the Philosophical Transactions of London. thermometer, that morning, till half past eight o'clock) I was assured by other observers, that, about two hours before sun-rise, it was considerably below zero! This surely might have rivalled the "frigus penetrabile adurens" of the Roman poet, supposed capable of piercing through the bones to the very marrow. Unaware, however, were the ancients of that admirable provision in the human frame, which constantly preserves the internal parts of the same equal temperature, in the depth of winter as in the midst of summer; within the polar circle as under the equator. On examining the liquors upon the garden wall, I found, to my astonishment, all of them (except the alcohol and vitriolic æther) perfectly congealed: the first time I had ever seen wine, brandy, and spiritous liquors in a solid form! Experiment 4. Being desirous to try the effects of a high degree of artificial cold, added to the natural cold that now prevailed, an ounce of quicksilver, in an open phial, was placed in a frigorific mixture, consisting of snow, with vitriolic acid, &c. In the act of solution (during which the greatest degree of cold is generated) the thermometer was immersed in the frigorific mixture, which, in a few seconds, sunk the quicksilver far below zero, even into the bulb of the thermometer, when the quicksilver, both in the thermometer and in the phial, suddenly assumed the appearance of a thin plate of lead, placed on the surface of fluid quicksilver below, which doubtless was a real mark of incipient congelation. But unfortunately, at |